Tracking Your Baby’s Growth at 16, 20, and 24 Weeks
The weeks between 16 and 24 of pregnancy mark a remarkable period of development as your baby grows from the size of an avocado to a cantaloupe. Many parents consider this the “golden period” of the second trimester, when pregnancy discomforts often ease while exciting developmental milestones occur.
Key Highlights
Here’s what makes this period so special:
- Around week 16, your baby develops the ability to hear your voice for the first time
- Most mothers feel their baby’s first movements between 16-22 weeks, often described as “flutters”
- The 20-week appointment typically includes a detailed anatomy scan and option to learn baby’s sex
- By 24 weeks, your baby weighs over a pound and has reached viability
- This period is ideal for bonding as your baby develops more refined senses
Understanding Changes: Your Baby’s Sensory World Begins
By week 16, your baby has reached a significant milestone in sensory development—the ability to hear. At approximately 4.5-5.5 inches long (about the size of an avocado), your little one can now detect sounds from outside the womb, including your voice. The cochlea, the spiral-shaped part of the inner ear responsible for hearing, becomes fully developed, enabling this remarkable connection. According to the American Pregnancy Association, your baby may even respond to loud noises with an increase in movement.
This is the perfect time to begin talking, singing, or reading to your baby, fostering an early bond that will continue after birth. Research shows that newborns can recognize their mother’s voice after delivery because of this early exposure. Your baby’s hearing will continue to sharpen throughout the remaining weeks of your pregnancy, creating a growing awareness of the world outside.
Understanding Changes: Those First Magical Movements
For many parents, feeling their baby move for the first time is one of the most emotional moments of pregnancy. First-time mothers typically notice these movements, often called “quickening,” between 18-22 weeks, while experienced mothers may feel them earlier, around 16-18 weeks. These initial sensations are frequently described as flutters, bubbles popping, or a light tapping from within.
Don’t worry if you haven’t felt movement by week 20—factors like placenta position, body composition, and activity level can all affect when movements become noticeable. By weeks 20-24, movements become more coordinated and stronger as your baby’s neuromuscular system matures. The Mayo Clinic notes that while early movements may be sporadic, by week 24, you’ll likely establish more consistent patterns as your baby develops sleep-wake cycles. These movements serve as reassuring signs of your baby’s well-being and development during the 2nd trimester.
Your Body & Baby: The Halfway Milestone
Reaching week 20 marks the halfway point in your pregnancy journey—a significant milestone worth celebrating. This period often coincides with one of the most anticipated appointments: the detailed anatomy scan. During this ultrasound, healthcare providers examine your baby’s organs, limbs, placenta placement, and overall growth. The scan typically takes 30-45 minutes as technicians capture detailed images of your baby’s developing systems.
For many parents, this appointment offers the opportunity to learn their baby’s sex, if desired. It’s helpful to decide beforehand whether you want this information, as the ultrasound technician will need to know your preference. Beyond gender revelation, this appointment provides important reassurance about your baby’s development and can detect any potential concerns that might require additional monitoring. The images are often remarkably clear, showing facial features and movements that make your pregnancy feel more real than ever before.
Your Body & Baby: Growth from 16-24 Weeks
The transformation your baby undergoes between weeks 16 and 24 is truly remarkable. At week 16, your baby measures about 4.5 inches and weighs approximately 3-4 ounces. By week 20, that size nearly doubles to 6-10 inches and 9-11 ounces. Finally, at week 24, your baby reaches the length of a cantaloupe (about 12 inches) and weighs over a pound—a 400% increase from week 16!
During this period, your baby’s sleep patterns also begin to emerge. You can learn more about these developing patterns in our article about how baby sleep patterns develop during the second trimester. By week 24, your baby has reached viability—meaning with intensive medical care, survival outside the womb becomes possible. Your baby’s skin appears wrinkled and translucent at this stage, with visible blood vessels underneath. Lung development progresses significantly as specialized cells begin producing surfactant, a substance that will help your baby breathe after birth. These rapid developments explain why many women experience more energy needs and increased hunger during these weeks.
Healthy Living Tips: Managing Common Discomforts
While the second trimester is often considered the most comfortable period of pregnancy, some discomforts may still arise. Pregnancy headaches second trimester are common due to hormonal changes, increased blood volume, and sometimes stress or dehydration. To manage these headaches, try staying well-hydrated, maintaining regular sleep patterns, practicing relaxation techniques, and consulting your healthcare provider about pregnancy-safe pain relief options if needed.
Back pain may also become more noticeable as your center of gravity shifts with your growing belly. Practicing good posture, wearing supportive shoes, using pregnancy pillows during sleep, and gentle prenatal yoga can help alleviate this discomfort. Round ligament pain—sharp, stabbing sensations in your lower abdomen or groin—is another common experience as the ligaments supporting your uterus stretch. Changing positions slowly and applying warmth to the area can provide relief. The Cleveland Clinic recommends contacting your healthcare provider if any pain becomes severe or is accompanied by other concerning symptoms like fever or bleeding.
Healthy Living Tips: Bonding With Your Baby
These middle weeks of pregnancy offer wonderful opportunities to connect with your growing baby. Starting a daily ritual of talking or reading to your baby helps you bond while also familiarizing your little one with your voice. Some parents play music or gently tap on their belly and notice their baby responding to these interactions with movement.
Tracking your baby’s movement patterns can be both reassuring and bonding. Many healthcare providers recommend daily “kick counts” starting around week 24. You might find it helpful to use apps that help track the second trimester of pregnancy, including movement patterns. Creating a pregnancy journal or taking weekly photos can help you document this special time and create keepsakes to share with your child someday. Partners can participate in bonding by talking to the baby, feeling movements, and attending prenatal appointments. These simple practices nurture the parent-child relationship long before birth and create wonderful memories of your pregnancy journey.
Embracing This Special Time
The weeks from 16 to 24 represent a unique window in your pregnancy when your baby’s development accelerates dramatically, and you begin forming a tangible connection through movement and sound. This period bridges the early days when pregnancy might have felt abstract to the later stages when you’ll be preparing practically for your baby’s arrival.
Take time to savor these middle weeks, documenting changes, sharing experiences with loved ones, and tuning into your baby’s growing presence. While each pregnancy journey is unique, these weeks typically offer a blend of excitement, wonder, and increasing connection that many parents look back on fondly. As you move toward the third trimester, carry forward the bonds you’ve begun forming during this remarkable period of growth and discovery.
Sources
American College of Obstetricians and Gynecologists. Your Pregnancy and Childbirth Month to Month
Mayo Clinic. Pregnancy Week by Week
American Pregnancy Association. Pregnancy Week 16